This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The primary objectives of this study are to collect pilot data, in support of an upcoming NIH (R01) grant application, and to characterize the relationships between physical exercise, brain structure and function (as measured by MRI), cognition, and aging. Four groups of healthy normal adults will be contrasted: younger (aged 20-25 years) and older (60-65 years) regular exercisers and younger and older non-exercisers. It is hypothesized that (1) there will be a main effect of exercise status on brain structure and function, (2) there will be a main effect of age on both brain structure and function, and cognitive function, and (3) there will be an interaction between exercise status and age on cognitive function such that the effects of exercise status on cognitive function will be greater in the older age group. Limited MRI specific research to date indicates that aerobic exercise may preserve brain volume (gray and white matter in frontal regions) and associated cognitive capacity in elderly populations (Colcombe et al., 2003, 2006). One other study (Marks et al., 2007) suggests that greater aerobic fitness is associated with increased white matter integrity in key select brain regions. The proposed research study intends to corroborate and extend these findings by using multiple brain imaging techniques to determine the influence of exercise on: brain morphometry/volume, connectivity, activation, and perfusion. Aerobic fitness will be determined from a maximal oxygen consumption treadmill protocol;associated cognitive differences will be assessed using the following tasks: Reversal Learning, Stroop, and Weschler Memory test. To address a void in the current literature, and to explore potential effects of age, this investigation intends to also include a young population.